Update osu.Framework/Graphics/UserInterface/TextBox.cs
Update osu.Framework/Graphics/UserInterface/TextBox.cs

Co-authored-by: Susko3 <d9344bdab177eaca4e833e6729163d278118f25e@protonmail.com>
ppy/osu-framework,peppy/osu-framework,ppy/osu-framework,peppy/osu-framework,ppy/osu-framework,peppy/osu-framework